1. Field of the Invention
The field of art to which this invention pertains may be generally located in the class of devices relating to valves. Class 151, Valves and Valve Actuation, United States Patent Office Classification, appears to be the applicable general area of art to which the subject matter similar to this invention has been classified in the past.
2. Description of the Prior Art
This invention relates generally to ball valves, and in particular to a cut-off ball valve provided with a lockable security device. The lockable security device is operatively connected to the ball element of the valve to prevent undesired rotation of the ball element, and to automatically lock the ball element in the closed position of the valve when the ball element is turned to said closed position.
The ball valve of the present invention, with its lockable security device is adapted for use in water and heating systems, and it may be operated quickly at high pressures.
A problem commonly encountered in the use of ball valves for controlling the flow of a fluid is the difficulty of ensuring that the valve ball element is in the closed position, so as to avoid accidental or unintentional operations of the valve, which can change the pre-set or desired operative condition of the valve. U.S. Pat. No. 4,848,724 discloses a ball valve with a control lever locking mechanism wherein a manually operable lock is provided to retain the control lever and the ball element in a fully open position, a fully closed position, or in at least one intermediate operative position between the fully open and fully closed positions. A disadvantage with the ball valve control lever locking mechanism disclosed in the last mentioned patent is that it includes a ring shaped element which is adapted to engage stop members or protrusions on the valve body, to hold the control lever in a selected position, and it must be manually moved to a locking position when the valve control lever is moved to a fully closed position. The ring shaped element is difficult to manipulate when the control lever is moved from a fully open position to a fully closed position and vice versa. Another disadvantage of the control lever locking mechanism disclosed in the last mentioned patent is that two hands of the operator are required while moving the control lever to make sure that a correct adjusted position is obtained. One hand of a user is required to move the ring shaped element while the other hand is required to rotate the control lever, and such a two-handed operation can result in misplacing the control lever in an erroneous position.
It is a primary object of the present invention to provide a novel, lockable security device for a ball valve which overcomes the aforementioned problem and disadvantages of the ball valve control lever locking mechanism set forth above.
It is another object of the present invention to provide a ball valve with a lockable security device which automatically locks the ball valve control lever in a fully closed position when the lever is rotated to that position.
It is a further object of the present invention to provide a ball valve with a lockable security device which may include a supplementary locking means when the valve control lever is in a fully closed position.